Which flow diagram correctly describes the effect of tar entering lungs?

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Tar is a cause of Chronic obstructive pulmonary disease (COPD) which includes both chronic bronchitis and emphysema and it is also a carcinogen, too. So, I think that A, B, and C would be correct answers, but the solution is A. Why B and C are incorrect?

Thank you very much!


COPD is not caused by an infection (which would require a pathogen) but by the inflammation reaction the body triggers because of the tar particles. Thus the statement "mucus accumulated causing infection" does not correctly describe the effect of tar on the lung. Consequently, B and C are incorrect.


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